Update:
As Hofmator was kind enough to point out, I was confusing qr with quotemeta, which are two entirely different beasties, though for some reason I had the two confused.

Using \Q and \E is still one way to avoid having to go backslash crazy on your regex, though, and this was the original inspiration for this follow-up.

The original post is preserved below.
Using qr() on \b is going to look for "backslash,b" instead of a word break. Try this instead: 
$ip = "192.168.3.5";

# ...

if ($line =~ /\b\Q$ip\E\b/)
{
     # ...
}

[download]
Using \Q and \E ensure that no matter what $ip has in it, it will be matched very literally. You could also take this approach: 
$ip = qr("192.168.3.5");

# ...

if ($line =~ /\b$ip\b/)
{
     # ...
}

[download]
This makes sure that $ip is "regex-ready" before being used, by virtue of the qr() function.

In reply to Re^2: Saving Results of a while loop by tadman
in thread Saving Results of a while loop by dru145

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